<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>css实现各种形状</title>
  <style>
    div {
      margin: 0 auto;
      margin-top: 100px;
    }

    #square {
      width: 100px;
      height: 100px;
      background: red;
    }

    #rectangle {
      width: 200px;
      height: 100px;
      background: red;
    }

    #circle {
      width: 100px;
      height: 100px;
      background: red;
      border-radius: 50%
    }

    #oval {
      width: 200px;
      height: 100px;
      background: red;
      border-radius: 100px / 50px;
    }

    #triangle-up {
      width: 0;
      height: 0;
      border-left: 50px solid transparent;
      border-right: 50px solid transparent;
      border-bottom: 100px solid red;
    }

    #triangle-down {
      width: 0;
      height: 0;
      border-left: 50px solid transparent;
      border-right: 50px solid transparent;
      border-top: 100px solid red;
    }

    #triangle-left {
      width: 0;
      height: 0;
      border-top: 50px solid transparent;
      border-right: 100px solid red;
      border-bottom: 50px solid transparent;
    }

    #triangle-right {
      width: 0;
      height: 0;
      border-top: 50px solid transparent;
      border-left: 100px solid red;
      border-bottom: 50px solid transparent;
    }

    #triangle-topleft {
      width: 0;
      height: 0;
      border-top: 100px solid red;
      border-right: 100px solid transparent;
    }

    #triangle-topright {
      width: 0;
      height: 0;
      border-top: 100px solid red;
      border-left: 100px solid transparent;
    }

    #triangle-bottomleft {
      width: 0;
      height: 0;
      border-bottom: 100px solid red;
      border-right: 100px solid transparent;
    }

    #triangle-bottomright {
      width: 0;
      height: 0;
      border-bottom: 100px solid red;
      border-left: 100px solid transparent;
    }

    #curvedarrow {
      position: relative;
      width: 0;
      height: 0;
      border-top: 9px solid transparent;
      border-right: 9px solid red;
      transform: rotate(10deg);
    }

    #curvedarrow:after {
      content: "";
      position: absolute;
      border: 0 solid transparent;
      border-top: 3px solid red;
      border-radius: 20px 0 0 0;
      top: -12px;
      left: -9px;
      width: 12px;
      height: 12px;
      transform: rotate(45deg);
    }

    #trapezoid {
      border-bottom: 100px solid red;
      border-left: 25px solid transparent;
      border-right: 25px solid transparent;
      height: 0;
      width: 100px;
    }

    #parallelogram {
      width: 150px;
      height: 100px;
      transform: skew(20deg);
      background: red;
    }

    #star-six {
      width: 0;
      height: 0;
      border-left: 50px solid transparent;
      border-right: 50px solid transparent;
      border-bottom: 100px solid red;
      position: relative;
    }

    #star-six:after {
      width: 0;
      height: 0;
      border-left: 50px solid transparent;
      border-right: 50px solid transparent;
      border-top: 100px solid red;
      position: absolute;
      content: "";
      top: 30px;
      left: -50px;
    }

    #star-five {
      margin: 50px 0;
      position: relative;
      display: block;
      color: red;
      width: 0px;
      height: 0px;
      border-right: 100px solid transparent;
      border-bottom: 70px solid red;
      border-left: 100px solid transparent;
      transform: rotate(35deg);
    }

    #star-five:before {
      border-bottom: 80px solid red;
      border-left: 30px solid transparent;
      border-right: 30px solid transparent;
      position: absolute;
      height: 0;
      width: 0;
      top: -45px;
      left: -65px;
      display: block;
      content: '';
      transform: rotate(-35deg);
    }

    #star-five:after {
      position: absolute;
      display: block;
      color: red;
      top: 3px;
      left: -105px;
      width: 0px;
      height: 0px;
      border-right: 100px solid transparent;
      border-bottom: 70px solid red;
      border-left: 100px solid transparent;
      transform: rotate(-70deg);
      content: '';
    }

    #pentagon {
      position: relative;
      width: 54px;
      box-sizing: content-box;
      border-width: 50px 18px 0;
      border-style: solid;
      border-color: red transparent;
    }

    #pentagon:before {
      content: "";
      position: absolute;
      height: 0;
      width: 0;
      top: -85px;
      left: -18px;
      border-width: 0 45px 35px;
      border-style: solid;
      border-color: transparent transparent red;
    }

    #hexagon {
      width: 100px;
      height: 57.735px;
      background: red;
      position: relative;
    }

    #hexagon::before {
      content: "";
      position: absolute;
      top: -28.8675px;
      left: 0;
      width: 0;
      height: 0;
      border-left: 50px solid transparent;
      border-right: 50px solid transparent;
      border-bottom: 28.8675px solid red;
    }

    #hexagon::after {
      content: "";
      position: absolute;
      bottom: -28.8675px;
      left: 0;
      width: 0;
      height: 0;
      border-left: 50px solid transparent;
      border-right: 50px solid transparent;
      border-top: 28.8675px solid red;
    }

    #octagon {
      width: 100px;
      height: 100px;
      background: red;
      position: relative;
    }

    #octagon:before {
      content: "";
      width: 100px;
      height: 0;
      position: absolute;
      top: 0;
      left: 0;
      border-bottom: 29px solid red;
      border-left: 29px solid #eee;
      border-right: 29px solid #eee;
    }

    #octagon:after {
      content: "";
      width: 100px;
      height: 0;
      position: absolute;
      bottom: 0;
      left: 0;
      border-top: 29px solid red;
      border-left: 29px solid #eee;
      border-right: 29px solid #eee;
    }

    #heart {
      position: relative;
      width: 100px;
      height: 90px;
    }

    #heart:before,
    #heart:after {
      position: absolute;
      content: "";
      left: 50px;
      top: 0;
      width: 50px;
      height: 80px;
      background: red;
      border-radius: 50px 50px 0 0;
      transform: rotate(-45deg);
      transform-origin: 0 100%;
    }

    #heart:after {
      left: 0;
      transform: rotate(45deg);
      transform-origin: 100% 100%;
    }

    #infinity {
      position: relative;
      width: 212px;
      height: 100px;
      box-sizing: content-box;
    }

    #infinity:before,
    #infinity:after {
      content: "";
      box-sizing: content-box;
      position: absolute;
      top: 0;
      left: 0;
      width: 60px;
      height: 60px;
      border: 20px solid red;
      border-radius: 50px 50px 0 50px;
      transform: rotate(-45deg);
    }

    #infinity:after {
      left: auto;
      right: 0;
      border-radius: 50px 50px 50px 0;
      transform: rotate(45deg);
    }

    #diamond {
      width: 0;
      height: 0;
      border: 50px solid transparent;
      border-bottom-color: red;
      position: relative;
      top: -50px;
    }

    #diamond:after {
      content: '';
      position: absolute;
      left: -50px;
      top: 50px;
      width: 0;
      height: 0;
      border: 50px solid transparent;
      border-top-color: red;
    }

    #diamond-shield {
      width: 0;
      height: 0;
      border: 50px solid transparent;
      border-bottom: 20px solid red;
      position: relative;
      top: -50px;
    }

    #diamond-shield:after {
      content: '';
      position: absolute;
      left: -50px;
      top: 20px;
      width: 0;
      height: 0;
      border: 50px solid transparent;
      border-top: 70px solid red;
    }

    #diamond-narrow {
      width: 0;
      height: 0;
      border: 50px solid transparent;
      border-bottom: 70px solid red;
      position: relative;
      top: -50px;
    }

    #diamond-narrow:after {
      content: '';
      position: absolute;
      left: -50px;
      top: 70px;
      width: 0;
      height: 0;
      border: 50px solid transparent;
      border-top: 70px solid red;
    }

    #cut-diamond {
      border-style: solid;
      border-color: transparent transparent red transparent;
      border-width: 0 25px 25px 25px;
      height: 0;
      width: 50px;
      box-sizing: content-box;
      position: relative;
      margin: 20px 0 50px 0;
    }

    #cut-diamond:after {
      content: "";
      position: absolute;
      top: 25px;
      left: -25px;
      width: 0;
      height: 0;
      border-style: solid;
      border-color: red transparent transparent transparent;
      border-width: 70px 50px 0 50px;
    }

    #egg {
      display: block;
      width: 126px;
      height: 180px;
      background-color: red;
      border-radius: 50% 50% 50% 50% / 60% 60% 40% 40%;
    }

    #pacman {
      width: 0px;
      height: 0px;
      border-right: 60px solid transparent;
      border-top: 60px solid red;
      border-left: 60px solid red;
      border-bottom: 60px solid red;
      border-top-left-radius: 60px;
      border-top-right-radius: 60px;
      border-bottom-left-radius: 60px;
      border-bottom-right-radius: 60px;
    }

    #talkbubble {
      width: 120px;
      height: 80px;
      background: red;
      position: relative;
      -moz-border-radius: 10px;
      -webkit-border-radius: 10px;
      border-radius: 10px;
    }

    #talkbubble:before {
      content: "";
      position: absolute;
      right: 100%;
      top: 26px;
      width: 0;
      height: 0;
      border-top: 13px solid transparent;
      border-right: 26px solid red;
      border-bottom: 13px solid transparent;
    }

    #rss {
      width: 20em;
      height: 20em;
      border-radius: 3em;
      background-color: #ff0000;
      font-size: 14px;
    }

    #rss:before {
      content: '';
      z-index: 1;
      display: block;
      height: 5em;
      width: 5em;
      background: #fff;
      border-radius: 50%;
      position: relative;
      top: 11.5em;
      left: 3.5em;
    }

    #rss:after {
      content: '';
      display: block;
      background: #ff0000;
      width: 13em;
      height: 13em;
      top: -2em;
      left: 3.8em;
      border-radius: 2.5em;
      position: relative;
      box-shadow:
        -2em 2em 0 0 #fff inset,
        -4em 4em 0 0 #ff0000 inset,
        -6em 6em 0 0 #fff inset
    }

    #burst-12 {
      background: red;
      width: 80px;
      height: 80px;
      position: relative;
      text-align: center;
    }

    #burst-12:before,
    #burst-12:after {
      content: "";
      position: absolute;
      top: 0;
      left: 0;
      height: 80px;
      width: 80px;
      background: red;
    }

    #burst-12:before {
      transform: rotate(30deg);
    }

    #burst-12:after {
      transform: rotate(60deg);
    }

    #burst-8 {
      background: red;
      width: 80px;
      height: 80px;
      position: relative;
      text-align: center;
      transform: rotate(20deg);
    }

    #burst-8:before {
      content: "";
      position: absolute;
      top: 0;
      left: 0;
      height: 80px;
      width: 80px;
      background: red;
      transform: rotate(135deg);
    }

    #yin-yang {
      width: 96px;
      box-sizing: content-box;
      height: 48px;
      background: #eee;
      border-color: red;
      border-style: solid;
      border-width: 2px 2px 50px 2px;
      border-radius: 100%;
      position: relative;
    }

    #yin-yang:before {
      content: "";
      position: absolute;
      top: 50%;
      left: 0;
      background: #eee;
      border: 18px solid red;
      border-radius: 100%;
      width: 12px;
      height: 12px;
      box-sizing: content-box;
    }

    #yin-yang:after {
      content: "";
      position: absolute;
      top: 50%;
      left: 50%;
      background: red;
      border: 18px solid #eee;
      border-radius: 100%;
      width: 12px;
      height: 12px;
      box-sizing: content-box;
    }

    #badge-ribbon {
      position: relative;
      background: red;
      height: 100px;
      width: 100px;
      border-radius: 50px;
    }

    #badge-ribbon:before,
    #badge-ribbon:after {
      content: '';
      position: absolute;
      border-bottom: 70px solid red;
      border-left: 40px solid transparent;
      border-right: 40px solid transparent;
      top: 70px;
      left: -10px;
      transform: rotate(-140deg);
    }

    #badge-ribbon:after {
      left: auto;
      right: -10px;
      transform: rotate(140deg);
    }

    #space-invader {
      box-shadow: 0 0 0 1em red,
        0 1em 0 1em red,
        -2.5em 1.5em 0 .5em red,
        2.5em 1.5em 0 .5em red,
        -3em -3em 0 0 red,
        3em -3em 0 0 red,
        -2em -2em 0 0 red,
        2em -2em 0 0 red,
        -3em -1em 0 0 red,
        -2em -1em 0 0 red,
        2em -1em 0 0 red,
        3em -1em 0 0 red,
        -4em 0 0 0 red,
        -3em 0 0 0 red,
        3em 0 0 0 red,
        4em 0 0 0 red,
        -5em 1em 0 0 red,
        -4em 1em 0 0 red,
        4em 1em 0 0 red,
        5em 1em 0 0 red,
        -5em 2em 0 0 red,
        5em 2em 0 0 red,
        -5em 3em 0 0 red,
        -3em 3em 0 0 red,
        3em 3em 0 0 red,
        5em 3em 0 0 red,
        -2em 4em 0 0 red,
        -1em 4em 0 0 red,
        1em 4em 0 0 red,
        2em 4em 0 0 red;
      background: red;
      width: 1em;
      height: 1em;
      overflow: hidden;
      margin: 50px 0 70px 65px;
    }

    #tv {
      position: relative;
      width: 200px;
      height: 150px;
      margin: 20px 0;
      background: red;
      border-radius: 50% / 10%;
      color: white;
      text-align: center;
      text-indent: .1em;
    }

    #tv:before {
      content: '';
      position: absolute;
      top: 10%;
      bottom: 10%;
      right: -5%;
      left: -5%;
      background: inherit;
      border-radius: 5% / 50%;
    }

    #chevron {
      position: relative;
      text-align: center;
      padding: 12px;
      margin-bottom: 6px;
      height: 60px;
      width: 200px;
    }

    #chevron:before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      height: 100%;
      width: 51%;
      background: red;
      transform: skew(0deg, 6deg);
    }

    #chevron:after {
      content: '';
      position: absolute;
      top: 0;
      right: 0;
      height: 100%;
      width: 50%;
      background: red;
      transform: skew(0deg, -6deg);
    }

    #magnifying-glass {
      font-size: 10em;
      display: inline-block;
      width: 0.4em;
      box-sizing: content-box;
      height: 0.4em;
      border: 0.1em solid red;
      position: relative;
      border-radius: 0.35em;
    }

    #magnifying-glass:before {
      content: "";
      display: inline-block;
      position: absolute;
      right: -0.25em;
      bottom: -0.1em;
      border-width: 0;
      background: red;
      width: 0.35em;
      height: 0.08em;
      transform: rotate(45deg);
    }

    #facebook-icon {
      background: red;
      text-indent: -999em;
      width: 100px;
      height: 110px;
      box-sizing: content-box;
      border-radius: 5px;
      position: relative;
      overflow: hidden;
      border: 15px solid red;
      border-bottom: 0;
    }

    #facebook-icon:before {
      content: "/20";
      position: absolute;
      background: red;
      width: 40px;
      height: 90px;
      bottom: -30px;
      right: -37px;
      border: 20px solid #eee;
      border-radius: 25px;
      box-sizing: content-box;
    }

    #facebook-icon:after {
      content: "/20";
      position: absolute;
      width: 55px;
      top: 50px;
      height: 20px;
      background: #eee;
      right: 5px;
      box-sizing: content-box;
    }

    #moon {
      width: 80px;
      height: 80px;
      border-radius: 50%;
      box-shadow: 15px 15px 0 0 red;
    }

    #flag {
      width: 110px;
      height: 56px;
      box-sizing: content-box;
      padding-top: 15px;
      position: relative;
      background: red;
      color: white;
      font-size: 11px;
      letter-spacing: 0.2em;
      text-align: center;
      text-transform: uppercase;
    }

    #flag:after {
      content: "";
      position: absolute;
      left: 0;
      bottom: 0;
      width: 0;
      height: 0;
      border-bottom: 13px solid #eee;
      border-left: 55px solid transparent;
      border-right: 55px solid transparent;
    }

    #cone {
      width: 0;
      height: 0;
      border-left: 70px solid transparent;
      border-right: 70px solid transparent;
      border-top: 100px solid red;
      border-radius: 50%;
    }

    #cross {
      background: red;
      height: 100px;
      position: relative;
      width: 20px;
    }

    #cross:after {
      background: red;
      content: "";
      height: 20px;
      left: -40px;
      position: absolute;
      top: 40px;
      width: 100px;
    }

    #base {
      background: red;
      display: inline-block;
      height: 55px;
      margin-left: 20px;
      margin-top: 55px;
      position: relative;
      width: 100px;
    }

    #base:before {
      border-bottom: 35px solid red;
      border-left: 50px solid transparent;
      border-right: 50px solid transparent;
      content: "";
      height: 0;
      left: 0;
      position: absolute;
      top: -35px;
      width: 0;
    }

    #pointer {
      width: 200px;
      height: 40px;
      position: relative;
      background: red;
    }

    #pointer:after {
      content: "";
      position: absolute;
      left: 0;
      bottom: 0;
      width: 0;
      height: 0;
      border-left: 20px solid white;
      border-top: 20px solid transparent;
      border-bottom: 20px solid transparent;
    }

    #pointer:before {
      content: "";
      position: absolute;
      right: -20px;
      bottom: 0;
      width: 0;
      height: 0;
      border-left: 20px solid red;
      border-top: 20px solid transparent;
      border-bottom: 20px solid transparent;
    }

    #lock {
      font-size: 8px;
      position: relative;
      width: 18em;
      height: 13em;
      border-radius: 2em;
      top: 10em;
      box-sizing: border-box;
      border: 3.5em solid red;
      border-right-width: 7.5em;
      border-left-width: 7.5em;
      margin: 0 0 6rem 0;
    }

    #lock:before {
      content: "";
      box-sizing: border-box;
      position: absolute;
      border: 2.5em solid red;
      width: 14em;
      height: 12em;
      left: 50%;
      margin-left: -7em;
      top: -12em;
      border-top-left-radius: 7em;
      border-top-right-radius: 7em;
    }

    #lock:after {
      content: "";
      box-sizing: border-box;
      position: absolute;
      border: 1em solid red;
      width: 5em;
      height: 8em;
      border-radius: 2.5em;
      left: 50%;
      top: -1em;
      margin-left: -2.5em;
    }
  </style>
</head>

<body>
  <div></div>
  <div id="square"></div>
  <div id="rectangle"></div>
  <div id="circle"></div>
  <div id="oval"></div>
  <div id="triangle-up"></div>
  <div id="triangle-down"></div>
  <div id="triangle-left"></div>
  <div id="triangle-right"></div>
  <div id="triangle-topleft"></div>
  <div id="triangle-topright"></div>
  <div id="triangle-bottomleft"></div>
  <div id="triangle-bottomright"></div>
  <div id="curvedarrow"></div>
  <div id="trapezoid"></div>
  <div id="parallelogram"></div>
  <div id="star-six"></div>
  <div id="star-five"></div>
  <div id="pentagon"></div>
  <div id="hexagon"></div>
  <div id="octagon"></div>
  <div id="heart"></div>
  <div id="infinity"></div>
  <div id="diamond"></div>
  <div id="diamond-shield"></div>
  <div id="diamond-narrow"></div>
  <div id="cut-diamond"></div>
  <div id="egg"></div>
  <div id="pacman"></div>
  <div id="talkbubble"></div>
  <div id="burst-12"></div>
  <div id="burst-8"></div>
  <div id="yin-yang"></div>
  <div id="badge-ribbon"></div>
  <div id="space-invader"></div>
  <div id="tv"></div>
  <div id="chevron"></div>
  <div id="magnifying-glass"></div>
  <div id="facebook-icon"></div>
  <div id="moon"></div>
  <div id="flag"></div>
  <div id="cone"></div>
  <div id="cross"></div>
  <div id="base"></div>
  <div id="pointer"></div>
  <div id="lock"></div>
</body>

</html>